The present invention relates to a catalyst system and process for producing carboxylic acid blown polyurethane foams.
Polyurethane foams typically are produced by the reaction of organic isocyanates with polyester or polyether polyols in the presence of a blowing agent. Although fluorocarbons have typically been used in the past as the preferred blowing agent, fluorocarbons are believed to have a negative environmental impact.
As a result, more environmentally compatible blowing agents have been sought. For example, polyurethane foams may be produced using blowing agents selected from carboxylic acids and salts of carboxylic acids in the presence of catalysts and promoters which include amine compounds such as dimethylbenzylamine, tetramethylethylenediamine and triethylenediamine.
Many of these catalysts, however, suffer from the disadvantage of being relatively toxic to humans. This toxicity increases the hazard of producing polyurethanes. Many of these catalysts also have the disadvantage of having unpleasant odors. These odors make polyurethane producing processes extremely unpleasant, and may result in a product with a residual odor which makes the product unacceptable for its intended use. Although nontoxic or nonodoriferous catalysts are known in the art, in many instances these catalysts fail to yield polyurethane foams with appropriate properties, i.e., the foam is tight and the reactivity is delayed, when used in carboxylic acid blown polyurethane systems.